I know some folks with big hearts, but they don't even come close to the Antennae Galaxies: two colliding galaxies 45 million light years away, and tens of thousands of light years across!

These were probably two normal spiral galaxies, not too much different than our own Milky Way, which started colliding millions of years ago. Their combined gravity twisted and distorted their shape into what we see today.

Individual stars are too small to physically smack into each other, but giant clouds of dust and gas are much bigger targets. When they collide at these speeds (hundreds of km/sec!) they compress, collapse, and undergo a burst of star formation. All those pinkish clumps you see in this pictures are where thousands, perhaps millions, of stars are being born.

Eventually the galaxies will combine, the two melding into one bigger galaxy. A metaphor for Valentine's Day? Well, no, since the merger will be a vast chaotic realm of high-energy outbursts, massive turbulence, and an unpredictable future.

Oh, right. Nevermind.

My blog post about the Antennae.
Original Hubble release.

Image credit: NASA, ESA, and the Hubble Heritage Team STScI/AURA)-ESA/Hubble Collaboration.